A key benefit of systems modeling is the ability to easily request a plot of any system variable.  The Post_Request element makes this possible.

For common requests, MotionSolve provides the following types:

Marker IDs must be provided.  Another type, called ELEMENTAL_FORCE, is useful for requesting forces in specific elements, such as joints and bushings.

You can also define a Post_Request element as a mathematical expression in terms of system variables using MotionSolve functions.  Each request may define up to eight expressions stored in vectors labeled F1 through F8.

Finally, you may also use the REQSUB user-written subroutine REQSUB to define the request in C/C++ or FORTRAN.

When your model contains Post_Request elements, the plot data are written out to the ABF file.

MotionSolve provides the following graphic primitives to visualize bodies:

The SPDP element is used to visualize springs.  The Outline element is used to define an outline graphic using several markers which may belong to one or more bodies.

All animation data is written out to the H3D file.  When your model contains Post_Request of type MARKER_FORCE or ELEMENTAL_FORCE, MotionSolve also writes force and moment vectors to the H3D file so they can be visualized.